Exothermic reaction charge



f Aug. 21, 1.945.

c. A. cADwELL EXOTHERMIC REACTION CHARGE Filed Dec. 4, 1943 INVENTOR. CHARLES A.CADWELL BY m, MMM/[1 c, Q

ATTORNEYS Patented Aug., 21, 1945 EXOTHERMIC REACTION CHARGE Charles A. Cadwell, Cleveland Heights, Ohio, as-

signor to The Electric Company, Cleveland, Ohio Railway Improvement Ohio, a corporation of Application December 4, 1943, Serial No. 512,913

(Cl. 'l5-27) Claims.

The present improvements, relating cated to exothermic reaction charges,

as indihave more particular regard to the composition and method of using materials such as are described in my Patent No. 2,229,045, dated January 21, 1941, whereby highly heated molten metal is produced by exothermic reaction.

In such previous patent the composition disclosed is particularly designed for the production of molten copper to be used as a welding material, e. g. to attach the terminal of a copper bond to a steel rail. Inattempting to employ the well known exothermic reaction which occurs when a mixture of finely divided aluminum and copper oxide is ignited, the heat yield is sufficient to volatilize whatever copper might be expected from the reaction, and the invention disclosed in my previous patent has as its object the reduction, or rather the absorption, oi' such excessive heat energy so as to hold 'the copper yield to a molten rather than a gaseous form. According to the disclosure of said patent this may be accomplished by including in the reaction mixture sufficient copper as metal (preferably alloyed with the aluminum) to absorb a substantial amount of the heat generated by the reaction. As indicated, A

a charge composed of reaction material auch as the foregoing requires relatively high temperature ignition in order to be set oil, and for this purpose an igniting powder is placed on top of the charge, .such powder being of such composition that it may be ignited by a match or spark and will then generate sumcient heat in turn to ignite the main charge. Such powder should be inammable enough to Jump from a spark point to a quick spread over the whole surface of the charge. However, it has been found in many cases that instead of the reaction thus starting over the whole surface of the charge, it starts at a point, creates a crater and advances downwardly with other portions of the charge falling or rolling into the crater and reacting tardily. The result molten metal rather than the formation of a single compact body such as is desirable, particularly in aI rail bonding operation.

I have now discovered that an exothermic reaction oi' the character described may be satisfactorlly controlled so as to produce a single consolidated body of molten metal by making up a charge in layers the composition of which differ in reactivity. Specifically, by disposing on top of the main body of reaction material a small layer of like material having a higher intensity of reaction and then setting oil the latter by means of a further layer of action of the entire charge will be brought about in a much more uniform and satisfactory manner than has heretofore been thought possible.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and'particularly pointed out in the claims, the annexed drawing and the following description setting.

forth in detail certain means and one mode ot carrying out the invention, such disclosed means and mode illustrating. however, but one of various ways in which the principle of the invention may be used.

In said annexed drawing:

Fig. 1 is a sectional view of a rail bonding apparatus showing the manner in which my improved exothermic reaction charge may be employed in attaching the terminal of a rail bond to a rail;

Fig. 2 is a perspective view of a cartridge wherein the charge is disposed for convenient use in connection with such apparatus; and

Fig. 3 is a cross-sectional view of such cartridge indicating the disposition of its contents.

The composition which I prefer to employ for the main body of the charge comprises finely divided copper oxide and aluminum, the latter having sumcient copper alloyed therewith to abthe heat generated 'Additional copper` as metal may sorb a substantial amount o! by the reaction.

which will be found 'ed at the center from partially oxidized copper. while the surface may be black, highly oxidized and very conducive to quick ignition and combustion. If, however, the powder has been much tumbled and agitated as in a mechanical mixer, the soft black surfaced grain will become a hard surfaced redder grain plus a quantity of segregated fine black dust. Accordingly the oxide content of the powder may be varied by employing a selected grain size. For

example, powder that will pass through a 30- ignition powder, re-

-described in my aforesaid paient as there constiuting the entire reaction mass, such body being adapted to yield molten copper h'aving a sumciently high temperature to effect the welding of a bond terminal to a rail. Thus such main body l of the charge may comprise a mixture of about 40 parts of copper oxide and about 17 parts of aluminum including copper alloyed therewith in amount at least equal to the amount of aluminum.

In counterdistinction to the foregoing, the composition of the layer 5 is such as to produce a substantially higher temperature. To secure this, a convenient procedure is to use as the copper oxide component, copper scale of line particle size such as will pass a y30 mesh screen. As explained above, such .powder will have a low content of metallic copper and a high content of copper oxide. It is also desirable to employ an alloy in vwhich the copper content is lower than that of the alloy used in the main body of the charge, e. g. a. 60-40 alloy instead of a 65-35 alloy.

The rail bonding apparatus illustrated in Fig. l comprises a combined mold and crucible block I0 in which the crucible or reaction chamber II is connected with the mold cavity I2 by means of a sprue I3. Such mold cavity is open on one side and formed to hold the terminal I4 of the .rail bond against the head I5 of a rail or other part to which such terminal is to be welded. During the welding operation the mold is resiliently held against the rail head by a clamp arm I8 and interposed spring member I1.

A cup-shaped plug I 8 composed of metal which lwill be melted by the heat of th'e reaction in the crucible chamber is inserted at the bottom of the latter so as to retain the charge in such chamber until the reaction is complete.

For the purpose of 'properly placing the charge in the crucible, a hingedcover I9 which normally serves to close the upper end thereof is provided with a central opening 20, aligned with the axis of the crucible chamber, anupwardly and outwardly flaring rim 2l surrounding such opening.y

The opening 2i! is of smaller diameter than the container I in which the charge is packaged as above described, so that when such container, following removal of cap 3, is placed in an inverted position within rim 2l as shown in dotted outline in Fig. l, its contents will be discharged into the crucible chamber and assume the form ot a slightly mounded body of which the lower portion is composed of the main body 6 of the charge, on the top of which successive thin layers will be superimposed composed of layers 5 and 4 respec-` tively of the charge. Iii-ted as by `a spark, ignition of the layer 5 of high intensity powder will immediately follow and because of the composition of such layer the ignition will extend through the entire layer.

, The latter acts as a booster for the layer of ignition powder, overcoming the ignition resistance of the main body 6 of reaction material by flooding its entire top surface with a flash of high in- If now such layer l be igtensity heat. Any streaky ignition of such main body of reaction material is thus avoided. but on the contrary ignition proceeds uniformly downwardly therethrough across the entire section of the mass. The result is the production of a collected body of molten metal in the bottom of the cruoible chamber which, as the plug I8 yields, is discharged through the sprue into the mold as a compact falling body rather than as a owing stream. It thus becomes possible to control quite exactly the amount of heat'applied to the welding operation so as to insure the proper attachment of the bond terminal to the rail head without dissolving iron from the surface of the latter or leaving porositles in the resulting cast head.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the means and the step herein disclosed, provided those stated by any of the following claims or their equivalent be employed.

I, therefore, particularly point out and distinctly claim as my invention:

l. A self-propagating exothermic reaction charge comprising `two contiguously disposed bodies of material wherein a metallic oxide is intermixed with a metallic element capable upon being heated of reducing such oxide to produce molten metal, the amount of such metallic element in leach body being suilicient substantially to reduce such intermixed oxide to metal upon ignition of the charge arid one of said bodies being relatively smaller and having a higher intensity of reaction than the other, main body.

2. A self-propagating exothermic reaction charge comprising two contguously disposed bodies of material wherein a metallic oxide is intermixed with a metallic element.y capable upon being heated of reducing such oxide to produce molten metal the amount of such metallic element in each body being sufficient substantially to reduce such intermixedoxide to metal upon ignition of the charge, one of said bodies being relatively smaller and having a higher intensity of reaction than the other, main body, and a small body of readily ignitable material contiauous to such smaller body of reaction material.

3. A package of material for use in a selfpropagating exothermic reaction comprising an elongated container, a main body oi' material wherein a metallic oxide is intermixed with a metallic element capable upon being heated o! reducing such oxide to produce molten metal. such body of material extending from one end of saidy containery towards the other, and a contiguously located, relatively smaller body of such metallic oxide and intermixedmetallc element having a higher intensity yof reaction the amount ofsuch metallic element in each body being sumcient substantially to reduce such intermixed oxide to metal upon ignition of the charge.

d. A package of material for use in a selfpropagating exothermic reaction comprising an elongated container, a main body of materialwherein a metallic oxide is intermixed with a metallic element capable upon being heated of relayer of readily ignitabie material contiguous to such last-mentioned body, the first-mentioned end of said container being openable for discharge of its contents into a reaction chamber.

5. In a method of controlling a self-propagating exothermic reaction of the character described, the steps which comprise placing in a Crucible a main body of material wherein a metallic oxide is intermixed with a metallic element capable upon being heated of reducing such oxide to produce molten metal, such body a layer of such metallic oxide and intermixed metallic element having a higher intensity of reaction the amount oi' such metallic element in each body being suilicient substantially to reduce such intermixed oxide to metal upon' ignition of the charge. and setting oil such layer which in turn sets of! such main body of reaction material.

6. In a method of controlling a sell!-propagar;'-A ing exothermic reaction of the character tie-lv disposing on top of scribed, the steps which comprise placing' in a crucible a main body of material wherein a metallic oxide is intermixed with a metallic element capable upon being heated .of reducing such oxide to produce molten metal, disposing on top of auch body a relatively small layer o1' such metallic oxide and' intermixed metallic element having a higher intensity of reaction the amount of such metallic element in each body beim sumcient substantially to reduce such intermixed oxide to metal upon ignition ofthe charge, disposing on top of such layer a second relativelyl small layer of readily ignitable material, and then igniting such last-mentioned layer.

7. An exothermicv reaction charge comprising two contiguously disposed bodies ot intermixed. finely divided copper oxide and aluminum, the

latter being in amount suillcient substantially to reduce such oxide to metal upon ignition of the charge, one oi' said bodies being relatively smaller than the other and the copper oxide therein having a higher oxygen content than in such other, larger body.

8. An exothermic reaction charge comprising l two contiguously disposed bodies of intermixed, iinely divided copper oxide and aluminum, together with copper as metal the aluminum being in amount suillcient substantially to reduce such oxide to metal upon ignition of the charge, one of said bodies being relatively smaller than the other and the proportion of metallic copper therein being lower than in such other, larger body.

9. An exothermic reaction charge comprising two contiguously disposed `bodies of intermixed, iinely divided copper oxide and aluminum, the latter being in amount sufilcient substantially to reduce such oxide to metal upon ignition of the charge, one of said bodies being relatively smaller than the other and the size of the copper oxide particles therein being smaller than the size of such particles in the other, larger body.

l0. An exothermic reaction charge comprising two contiguously disposed bodies of intermixed, finely divided copper oxide and aluminum, the latter being in amount suillcient substantially to reduce such oxide to metal upon ignition of the charge and having copper alloyed therewith, one oi' said bodies being relatively smaller than the other, the size of the copper oxide particles in such smaller body being smaller than the size of such particles in such other, larger body, and the percentage of alloyed copper in such smaller body being likewise lower than in such larger body.

CHARLES A. CADWELL. 

